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Parallel DEVS & DEVSJAVA

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  1. Parallel DEVS & DEVSJAVA Presented by Ximeng Sun Mar 16, 2005

  2. References • Bernard P. Zeigler, Herbert Praehofer, and Tag Gon Kim. Theory of Modeling and Simulation. Academic Press, 2000. • Bernard P. Zeigler, Hessam S. Sarjoughian. Introduction to DEVS Modeling and Simulation with JAVA. http://www.acims.arizona.edu/SOFTWARE/software.shtml#DEVSJAVA

  3. Outline • Classic DEVS quick review • Why Parallel DEVS • Parallel DEVS Formalism • Atomic Model • Coupled Model • Closure under Coupling • Parallel DEVS Simulation Protocol • DEVSJAVA

  4. Classic DEVS quick review • Why Parallel DEVS • Parallel DEVS Formalism • Atomic Model • Coupled Model • Closure under Coupling • Parallel DEVS Simulation Protocol • DEVSJAVA

  5. Classic DEVS formalism

  6. DEVS in action

  7. Classic DEVS Coupled Model • . • . • D : the set of the components names. • Md : component DEVS models • EIC : external input coupling connects external inputs to component inputs • EOC : external output coupling connects component outputs to external outputs • IC : internal coupling connects component outputs to component inputs • .

  8. Classic DEVS quick review • Why Parallel DEVS • Parallel DEVS Formalism • Atomic Model • Coupled Model • Closure under Coupling • Parallel DEVS Simulation Protocol • DEVSJAVA

  9. Simple Pipeline model

  10. In Action

  11. Simultaneous events Q? For p1 which one is correct: δint –> δ ext or δext –> δint

  12. Indirect control • In Classic DEVS, only one would be chosen to execute by Select function. • Select: s –> p1 ≡ internal-transition-first • Select: s –> p0 ≡ external-transition-first

  13. If there’s a feedback…

  14. Lose input anyway • In Classic DEVS, always make the same choice among imminent components. • Select: s –> p0|p1 ≡ p0|p1 loses input

  15. Classic DEVS quick review • Why Parallel DEVS • Parallel DEVS Formalism • Atomic Model • Coupled Model • Closure under Coupling • Parallel DEVS Simulation Protocol • DEVSJAVA

  16. Parallel DEVS Atomic Model Xb is a set of bags over elements in X.

  17. Extensions of Classic DEVS • Allowing bags of inputs to the external function • Inputs may arrive in any order • Inputs with the same identity may arrive from one or more sources • Introducing confluent transition function • Localize collision tie-breaking control

  18. Confluent Transition Function • Collision: e = ta(s) • Classic DEVS: by Select function, at coupled model level – Global decision • Parallel DEVS: by , to each individual component – Local decision • Default: δcon(s,x) =δext(δint(s),0,x) • Or: δcon(s,x) =δint(δext(s,ta(s),x))

  19. Parallel DEVS Coupled Model • . • Identical to Classic DEVS, except for the absence of the Select function • X : a set of input events • Y : a set of output events • D : a set of component references • Md : a ParallelDEVS model, for each • Id : a set of influencers of d , for each • Zi,d: a set of output-to-input translation functions, for each

  20. Previous example

  21. Handling of imminent components in Parallel DEVS

  22. Problem in Classic DEVS solved

  23. Closure under Coupling of Parallel DEVS • Resultant of the coupled model: • Partition components into 4 sets: . imminent components . components about to receive inputs • (confluent components) • (imminent components receiving no input) • (components receiving input but not imminent) • . (remaining components)

  24. Closure under Coupling of Parallel DEVS • Functions of the Resultant: • Output Function: • Internal Transition Function:

  25. Closure under Coupling of Parallel DEVS • External Transition Function:

  26. Confluent Transition Function:

  27. Component is ? Recipient only: Confluent: Imminent only: Generic Transition Function

  28. Classic DEVS quick review • Why Parallel DEVS • Parallel DEVS Formalism • Atomic Model • Coupled Model • Closure under Coupling • Parallel DEVS Simulation Protocol • DEVSJAVA

  29. Hierarchical Model coordinator Coupled Model simulator coordinator Atomic Model Coupled Model simulator simulator Atomic Model Atomic Model

  30. Atomic Model Simulator

  31. Coupled Model Simulator

  32. Classic DEVS quick review • Why Parallel DEVS • Parallel DEVS Formalism • Atomic Model • Coupled Model • Closure under Coupling • Parallel DEVS Simulation Protocol • DEVSJAVA

  33. DEVSJAVA • DEVS-based, Object-Oriented Modeling and Simulation environment. • Written in Java and supports parallel execution on a uni-processor • Simulation Viewer for animating simulation in V2.7

  34. Package Diagram

  35. DEVSJAVA Class hierarchy of container classes

  36. DEVSJAVA Class hierarchy of DEVS classes

  37. Simple Pipeline in DEVSJAVA

  38. Simulation Viewer

  39. More complicated example

  40. Sources • DEVSJAVA - Modeling and Simulation environment for developing DEVS-based models by Hessam Sarjoughian, Bernard Zeigler. • http://www.acims.arizona.edu/SOFTWARE/software.shtml#DEVSJAVA (need a license)

  41. Question?